Which country has cities called "Helsinki" and "Oulu"?

C. Finland is the correct answer because Helsinki, the capital city of Finland, is well-known for its coastal location and vibrant cultural scene. Oulu, another major city in Finland, is located in the northern part of the country and is recognized for its technology and educational institutions. Both cities are significant within Finland, with Helsinki serving as the political, economic, and cultural hub, while Oulu plays a key role in the northern part of the nation.

In contrast, Sweden has cities like Stockholm and Gothenburg, Norway features Oslo and Bergen, and Denmark is known for Copenhagen and Aarhus, none of which include the cities Helsinki or Oulu. Understanding the geographical context and cultural significance of these cities helps clarify why Finland is the correct choice in this question.